Switch with contacts surrounded by a medium under pressure



Feb. 6,-1934. s. RUMP ET AL 1,945,916

SWITCH WITH CONTACTS SURROUNDED BY A MEDIUM UNDER PRESSURE Filed Sept. 20, 1930 Attorney Patented Feb. 6, 1934 UNITED STATES SWITCH WITH CONTACTS SURROUN DED BY A MEDIUM UNDER PRESSURE Sigurd Bump, Zurich, and Hans Thommen, Ennetbaden, Switzerland Application September 20, 1930, Serial No.

andin 6 Claims.

As is well known, the process of interrupting the current between the contacts of an oil switch is assisted by maintaining the medium surrounding them under high pressure. For this reason it has been proposed to keep the oil in an oil switch under high pressure. Attempts have also been made to bring about the interruption of the current in switches under compressed air. All these constructions have the disadvantage that 10 the pressure must be continuously maintained in the switch casing or tank and that the said switch casing or tank is only maintained air tight with great difllculty. It was then proposed to fill the tank with compressed air only for the period in which the rupture took place, the compressed air inlet valve being operated from either the voltage or current of the supply.

It is also well known that the are between contacts may be quenched by means of a conducting quenching medium contained in the arcing chamber and surrounding the contacts which, due to the increased current density is gasified or va.- porized between the contacts. In this manner a high pressure is generated in the arcing chamber at the point of interruption by the gas or vapour bubble which at the same time exerts a favourable cooling eflcct on the arc, causing the latter to be quickly and definitely quenched. Both conducting gases and liquids may be used as quenching mediums: For example a suitable medium is water to which in certain circumstances substances to render it conducting and glycerine are added.

The present invention relates to a switch, the contacts of which are surrounded by an arc quenching medium, the necessary pressure to which the said quenching medium is subjected being developed by the arc itself at the instant of rupture. A characteristic feature being that 40 the arcing chamber which surrounds the contacts is, in accordance with the invention, completely closed and, further, that the moving contact of the switch is not withdrawn from the said chamber.

Other features and advantages of the invention will be apparent from the following description and the accompanying drawing in which:

Figure 1 is a vertical view partly in section illustrating one embodiment of the invention; and Figure 2 is a vertical view in section illustrating a modified form of the invention.

Referring more particularly to the drawing by characters of reference, a designates an arcing chamber, in the bottom portion .of which the Germany September 23,

fixed switch contact I: is arranged, while the movable contact c is actuated by the switch lever o and guided by an insulating gland d situated in the cover of the chamber. In series with the switch contacts b c are also the contacts of an 0 air break switch e which is not opened until the arc in the chamber between the switch contacts b c is definitely ruptured. The type of air break switch most suitably used is one with plug contacts or knife contacts which remains with cerg5 tainty in a closed position until the rod I carrying the moving contact 0 has moved the distance required to interrupt the arc. The contacts of the air switch e are most suitably arranged in such a manner that the rod 1 is brought into its upper position withoutthe spring is being required. The spring 10 may also be built as a tension spring which causes the rod 1 and therefore the contact 0 to return to the closed position but not until the arc has been ruptured and the air break switch has opened. This latter arrangement has the advantage that upon reclosing, the current does not flow through the quenching medium and so evaporate it. In order to ensure that the explosion chamber is always 30 filled with liquid, a container a holding for example a store of water is advantageously provided and is connected by means of a tube 11. with the bottom of the chamber. The outlet of this tube is made small so that the pressure developed in the chamber will not be transmitted through it.

In special circumstances non-return valves may be built into the tube.

If the diameter of the arcing chamberis comparatively great, a residual current may flow through the conductive quenching medium from the fixed contact to the movable contact or such magnitudes as to make its interruption by the air break switch impossible. In order to prevent this'residual current from flowing the insulat ing lining h of the arcing chamber is constructed so that the gas or vapour bubble, generated when the interruption takes place, is deformed and caused to come in contact with the'side of the insulating lining in at least one place thereby in- 1 0 terrupting the conductive path for the flow of current by way of the quenching medium. Such deformation causes the remainder of the surface of the bubble to exertincreased pressure on the quenching medium and thereby facilitate interruption of the arc. This effect may be produced for example by giving to the lining a circular rib i of such thickness as to reduce its internal diameter at a position about midway between the top and bottom as is shown in Fig. 1 of the drawing. 11o

down the arcing chamber.

stantially increased while the interruption is also,

accelerated since the gas or vapour bubbles can expand only within very limited extents and the pressure in the arcing chamber therefore rises very rapidly. It is, however, quite possible to fill the arcing chamber only to a certain height with quenching medium.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:

1. In an electric circuit breaker apparatus, a closed substantially pressure-tight receptacle having a switch contact fixedly supported therein, a cooperating switch contact disposed for movement within said receptacle into connection with and disconnection from said fixed contact, the said contacts being immersed within an electricaliy conductive arc quenching liquid subject to vaporization and the creation of a gaseous bubble upon establishment of an are responsive to movement of said cooperating contact from connection with said fixed contact, a rib of insulating material disposed within said receptacle operative to restrict the vapor space along a portion of the path of movement of said cooperating contact to such extent as to cause deformation and contact of said bubble with said rib during movement of said cooperating contact from connection with said fixed contact to thereby interrupt the path for fiow of current between said contacts by way of said liquid.

2. In an electric circuit breaker apparatus, a closed substantially pressure-tight receptacle having a switch contact fixedly supported therein at one end thereof, a cooperating switch con tact disposed for movement within said receptacle into connection with and disconnection from the said fixed contact, the said contacts being immersed within an electrically conductive arc quenching liquid subject to vaporization and the creation of a gaseous bubble upon establishment ,of an are responsive to movement of said cooperating contact from connection with said fixed contact, and a rib of insulating material disposed within the said receptacle operative to restrict the vapor space along the longitudinal axis of said cooperating contact intermediate opposite ends of said receptacle to an extent such as to cause deformation and contact of said bubble with said rib to thereby interrupt the path for fiow of current between said contacts by way of said liquid.

3. In an electric circuit breaker apparatus, a closed substantially pressure-tight receptacle having a switch contact fixedly supported therein, a cooperating switch contact disposed for movement within said receptacle into connection with and disconnection from said fixed contact, the said contacts being immersed in an elec-.- trlcally conductive arc quenching liquid contained within said receptacle and constituting a path for the flow of current between said contacts upon disconnection thereof, the said liquid being subject to vaporization and the creation 0! a gaseous bubble upon the establishment of an are responsive to movement of said cooperating contact from connection with said fixed contact, and means disposed within said receptacle operative to restrict the vapor space along a portion of the path of movement oi. said cooperating contact to an extent such as to cause deformation and contact of said bubble with said means during movementoi said cooperating contact from connection with said fixed contact to thereby interrupt the path for fiow of current between said contacts by way of said liquid, the creation of said bubble being effective to increase the pressure of said liquid and thereby facilitate extinguishment of the said arc.

4. In an electric circuit breaker apparatus, a closed substantially pressure-tight receptacle having a switch contact fixedly supported therein, a cooperating switch contact disposed for movement within said receptacle to-and from connection with said fixed contact, the said contacts being immersed within an electrically conductive arc quenching liquid subject to vaporization and the creation of a gaseous bubble upon the establishment of an are responsive to movement of said cooperating contact from connection with said fixed contact, a cylindrical member of insulating material supported within said receptacle operative to restrict the vapor space about a portion of the path of movement of said cooperating contact to such extent as to cause deformation and contact of said bubble with the inner wall of said cylindrical member during movement of said cooperating contact from connection with said fixed contact to thereby interrupt the path for fiow of current between said contacts by way of said liquid.

5. In an electric circuit breaker apparatus, a closed receptacle having a switch contact fixedly supported therein, a cooperating switch contact disposed for movement within said receptacle into connection with and disconnection from said fixed contact, the said contacts being immersed in,

an electrically conductive arc quenching liquid contained within said receptacle and subject to vaporization upon the establishment of an are responsive to movement of said cooperating contact from connection with said fixed contact, a pair of movable disconnect switch contacts serially connectible with the first said contacts, the said cooperating contact being fixedly connected with one of said disconnect contacts and movable thereby to and from connection with said fixed contact, and means operable to move said disconnect contacts to and from connection with each other, the operations being such as to eflect movement of said cooperating contact from connection with said fixed contact prior to interruption of connection between said disconnect contacts, and the vaporization of said liquid being operative to quench the are between said cooper ating contact and said fixed contact before interruption of connection between said disconnect contacts.

6. In an electric circuit breaker apparatus. a

closed receptacle having a switch contact fixedly 4 ble upon establishment ofan are responsive to up movement of said cooperating contact from connection with said fixed contact, means disposed within said receptacle operative to restrict the vapor space along a portion of the path of movement of said cooperating contact to cause deformation and contact of said bubble with said means during movement of said cooperating contact from connection with said contact to thereby interrupt the path for flow of current between said contacts by way or said liquid, a pair of movable disconnect switch contacts serially connectible with the first said contacts, means operable to move said disconnect contacts to cause con- 

